Image forming apparatus, method of copying a document, and computer product

ABSTRACT

One digital copying machine is set as a parent machine and other copying machines are set as child machines. When documents are set both on an ADF of the parent machine and on an ADF of at least one child machine, a CPU of the parent machine performs two types of controls in parallel. In the first control, the ADF of the parent machine automatically feeds each of the original documents, the scanner of the parent machine reads images, and MEM-C or HDD of the parent machine stores the images. In the second control, the ADF of the child machine automatically feeds each of the original documents, the scanner of the child machine reads images, IEEE1394 1/F of the child machine transfers the images to the parent machine, and the MEM-C or the HDD of the parent machine stores the images.

BACKGROUND OF THE INVENTION

[0001] 1) Field of the Invention

[0002] The present invention relates to an image forming apparatus, acopying method, and a computer product for an image forming systemhaving a plurality of image forming apparatuses connected via acommunication line.

[0003] 2) Description of the Related Art

[0004] When a user makes a photocopy of a document using a conventionalimage forming apparatus like a digital copying machine, an automaticdocument feeder (ADF) is usually used. The user sets a desired number ofcopies by operating a key on an operation panel, sets original documentson a document tray, and then starts copying by pressing a start key onthe operation panel. The ADF automatically feeds each sheet of theoriginal documents set on the document tray. A scanner sequentiallyreads images from each of the documents, and image data read by thescanner are stored in an image memory, repeating the process until allof the documents set on the document tray are read. After the readingprocess is completed, the image data of the documents stored in theimage memory are sequentially transferred to a plotter (i.e. printer) tomake photocopies of the original documents by the preset number ofcopies.

[0005] On the other hand, if the ADF is not mounted on the image formingapparatus, the user sets a desired number of copies by operating a keyon the operation panel, sets one sheet of original documents on areading position, for example, on an exposure glass, of the scanner, andstarts copying by pressing the start key on the operation panel. Theuser repeats the process for each of the documents until all of thedocuments are copied. Each time when a user starts copying, the scannerreads image data from each document, and stores the image data in theimage memory. Then the image data are transferred to the plotterrepeatedly to make photocopies of the original document by the presetnumber of copies.

[0006] With the conventional image forming apparatus equipped with theADF, however, when the number of original documents to be copied exceedsa maximum number of sheets that can be accommodated on the documenttray, the user has to set a portion of the original documents that canbe processed at one time using the ADF, and then repeat the copyingprocess for the rest of the original documents. Consequently, theoperation efficiency is poor, and it takes much time to complete copyingall of the original documents.

[0007] With an image forming apparatus that is not equipped with theADF, the situation is even worse. When there are a large number oforiginal documents to be copied, the series of operation should beperformed with repetition by the number of original documents.Consequently, the operation efficiency is poor, and it takesconsiderable time to complete copying all of the documents.

SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to solve at least theproblems in the conventional technology.

[0009] The image forming system according to one aspect of the presentinvention comprises a first image forming apparatus and a second imageforming apparatus that are connected to each other via a communicationline, wherein the first image forming apparatus includes an imagereading unit that reads image data from a document, and the second imageforming apparatus includes an image storing unit that stores the imagedata, and a reading controller that controls the image reading unit toread the image data, and controls the image storing unit to store theimage data.

[0010] The image forming system according to another aspect of thepresent invention comprises a first image forming apparatus and a secondimage forming apparatus that are connected to each other via acommunication line, wherein the first image forming apparatus includes afirst image reading unit that reads image data from a document, and thesecond image forming apparatus includes a second image reading unit thatreads image data from a document, a image storing unit that stores theimage data, and a parallel reading controller that performs in parallela control of making the second image reading unit read image data from adocument that is set on the second image reading unit and making theimage storing unit store the image data, and a control of making thefirst image reading unit read image data from a document that is set onthe first image reading unit, transferring the image data to the secondimage forming apparatus, and making the image storing unit store theimage data.

[0011] The method of copying according to still another aspect of thepresent invention, which is employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, comprises setting one of the image forming apparatuses as a masterimage forming apparatus, and image forming apparatuses other than themaster image forming apparatus as slave image forming apparatuses,making the master image forming apparatus acquire image data from theslave image forming apparatus, and making the master image formingapparatus form an image based on the image data acquired from the slaveimage forming apparatus.

[0012] The method of copying according to still another aspect of thepresent invention, which is employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, comprises setting one of the image forming apparatuses as a masterimage forming apparatus, and image forming apparatuses other than themaster image forming apparatus as slave image forming apparatuses,making the master image forming apparatus acquire image data, making themaster image forming apparatus transfer the image data to the slaveimage forming apparatus, and making the slave image forming apparatusform an image based on the image data received from the master imageforming apparatus.

[0013] The method of copying according to still another aspect of thepresent invention, which is employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, comprises setting one of the image forming apparatuses as a masterimage forming apparatus, and image forming apparatuses other than themaster image forming apparatus as slave image forming apparatuses,making the master image forming apparatus acquire image data from theslave image forming apparatus, making the master image forming apparatusstore image data acquired from the master image forming apparatus andthe image data acquired from the slave image forming apparatus, makingthe master image forming apparatus transfer a part of the image datastored to the slave image forming apparatus, and making both the masterimage forming apparatus and the slave image forming apparatus formimages based on the image data transferred and the image data stored,respectively, in parallel.

[0014] The computer program according to still another aspect of thepresent invention, which is employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, makes a computer execute setting one of the image formingapparatuses as a master image forming apparatus, and image formingapparatuses other than the master image forming apparatus as slave imageforming apparatuses, making the master image forming apparatus acquireimage data from the slave image forming apparatus, and making the masterimage forming apparatus form an, image based on the image data acquiredfrom the slave image forming apparatus.

[0015] The computer program according to still another aspect of thepresent invention, which is employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, makes a computer execute setting one of the image formingapparatuses as a master image forming apparatus, and image formingapparatuses other than the master image forming apparatus as slave imageforming apparatuses, making the master image forming apparatus acquireimage data, making the master image forming apparatus transfer the imagedata to the slave image forming apparatus, and making the slave imageforming apparatus form an image based on the image data received fromthe master image forming apparatus.

[0016] The computer program according to still another aspect of thepresent invention, which is employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, makes a computer execute setting one of the image formingapparatuses as a master image forming apparatus, and image formingapparatuses other than the master image forming apparatus as slave imageforming apparatuses making the master image forming apparatus acquireimage data from the slave image forming apparatus making the masterimage forming apparatus store image data acquired from the master imageforming apparatus and the image data acquired from the slave imageforming apparatus making the master image forming apparatus transfer apart of the image data stored to the slave image forming apparatus andmaking both the master image forming apparatus and the slave imageforming apparatus form images based on the image data transferred andthe image data stored, respectively, in parallel.

[0017] The computer product according to still another aspect of thepresent invention, which is employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, contains a computer program that makes a computer execute settingone of the image forming apparatuses as a master image formingapparatus, and image forming apparatuses other than the master imageforming apparatus as slave image forming apparatuses, making the masterimage forming apparatus acquire image data from the slave image formingapparatus, and making the master image forming apparatus form an imagebased on the image data acquired from the slave image forming apparatus.

[0018] The computer product according to still another aspect of thepresent invention, which is employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, contains a computer program that makes a computer execute settingone of the image forming apparatuses as a master image formingapparatus, and image forming apparatuses other than the master imageforming apparatus as slave image forming apparatuses, making the masterimage forming apparatus acquire image data, making the master imageforming apparatus transfer the image data to the slave image formingapparatus, and making the slave image forming apparatus form an imagebased on the image data received from the master image formingapparatus.

[0019] The computer product according to still another aspect of thepresent invention, which is employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, contains a computer program that makes a computer execute settingone of the image forming apparatuses as a master image formingapparatus, and image forming apparatuses other than the master imageforming apparatus as slave image forming apparatuses, making the masterimage forming apparatus acquire image data from the slave image formingapparatus, making the master image forming apparatus store image dataacquired from the master image forming apparatus and the image dataacquired from the slave image forming apparatus, making the master imageforming apparatus transfer a part of the image data stored to the slaveimage forming apparatus, and making both the master image formingapparatus and the slave image forming apparatus form images based on theimage data transferred and the image data stored, respectively, inparallel.

[0020] The image forming apparatus according to still another aspect ofthe present invention, which is connected to another image formingapparatus via a communication line, comprises a remote image readingcontroller that acquires image data from the another image formingapparatus, and an image storing unit that stores the data.

[0021] The other objects, features and advantages of the presentinvention are specifically set forth in or will become apparent from thefollowing detailed descriptions of the invention when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a block diagram of a control system for a digitalcopying machine;

[0023]FIG. 2 is a schematic diagram of a digital copying machine as animage forming apparatus according to an embodiment of the presentinvention;

[0024]FIG. 3 is a layout of an operation panel of the digital copyingmachine;

[0025]FIG. 4 is an example display of a liquid crystal touch panel 31shown in FIG. 3 when a power is turned on;

[0026]FIG. 5 is an example of an image forming system having a pluralityof the digital copying machines;

[0027]FIG. 6 is a flowchart of an example of a processing operation of acontroller 200 shown in FIG. 1 according to the present invention;

[0028]FIG. 7 is an example of a normal process flow of image datawithout a compression process when the digital copying machine readsimages from a document;

[0029]FIG. 8 is another example of a normal process flow of image datawhen the digital copying machine reads images from a document;

[0030]FIG. 9 is an example of a process flow of image data with acompression process when the digital copying machine reads images from adocument;

[0031]FIG. 10 is another example of a process flow of image data with acompression process when the digital copying machine reads images from adocument;

[0032]FIG. 11 illustrates a control of image data storing to a scannermemory MEM-C 205 or a hard disk drive HDD 207 in the digital copyingmachine shown in FIG. 1;

[0033]FIG. 12 illustrates an example of a control of image data storingto the MEM-C 205 or the HDD 207 when a memory management mode is set ina digital copying machine that is set as a parent machine; and

[0034]FIG. 13 illustrates another example of a control of image datastoring to the MEM-C 205 or the HDD 207 when a memory management mode isset in a digital copying machine that is set as a parent machine.

DETAILED DESCRIPTION

[0035] Exemplary embodiments of an image forming apparatus, a copyingmethod, a computer program, and a computer product for an image formingsystem of the present invention are explained in detail with referenceto the accompanying drawings.

[0036]FIG. 2 is a schematic configuration of one example mechanismsection of the digital copying machine such as a multifunction printer(MFP) as an image forming apparatus according to the present invention.

[0037] An ADF 1 is mounted on an upper part of a main body of thisdigital copying machine. A finisher 100 as a post processor is connectedto a side of the copying machine. An operation panel 30 shown in FIG. 3is provided on a front upper surface of the copying machine main body.

[0038] Copy operation of this digital copying machine will be explainednext. A document is set on an document tray 2 of the ADF 1 of thedigital copying machine, with an image surface facing upward. An userpresses a print key (i.e., start key) 34 on the operation panel 30 in acopying mode. Then, a feed roller 3 and a feed belt 4 sequentially feedeach sheet of original document onto an exposure glass 6 starting fromthe bottom of the document, thereby to set the sheets at a predeterminedposition. A scanner (i.e., an image reading unit) 50 reads an image fromeach sheet of the original document. The feed belt 4 and a dischargingroller 5 discharge the read sheets of the document.

[0039] Each time when an image is read from one sheet of originaldocument, a document set detector 7 detects whether there is a nextsheet of original document on the document tray 2. When there is a nextsheet of original document, the feed roller 3 and the feed belt 4 feedthe sheet onto the exposure glass 6 in a similar manner that for thepreceding sheet of original document. Thereafter, a similar operation isrepeated.

[0040] A common motor (not shown) drives the feed roller 3, the feedbelt 4, and the discharging roller 5.

[0041] A first paper feeder 11, a second paper feeder 12, and a thirdpaper feeder 13 feed transfer sheets that are mounted on a first paperfeed tray 8, a second paper feed tray 9, and a third paper feed tray 10respectively. A longitudinal conveyer unit 14 conveys a transfer sheetto a position where the sheet is in contact with a photosensitive drum15. The longitudinal conveyer unit 14 selects any one of the paper feedtrays 8 to 10, and feeds the transfer sheet.

[0042] The document image data (i.e., image information) read by thescanner 50 is temporarily stored in an MEM-C 205 or an HDD 207 as theimage memories shown in FIG. 1. The image data is then transferred to awriting unit 57 within a plotter 80 as the image forming unit. Thewriting unit 57 emits a laser beam to write the image data onto thesurface of the photosensitive drum 15 that is charged in advance by acharger (not shown). When the image-data written portion passes througha developing unit 27, the developing unit 27 forms a toner image ontothis portion.

[0043] Alternatively, the document image data read by the scanner 50 isstored in the MEM-C 205 or the HDD 207. When all the document images areread, the image data are sequentially transferred to the writing unit 57within the plotter 80. The writing unit 57 emits a laser beam to writethe image data onto the surface of the photosensitive drum 15 charged inadvance. When the image-data written portion passes through thedeveloping unit 27, the developing unit 27 forms a toner image onto thisportion.

[0044] A conveyer belt (i.e. transfer belt) 16 conveys the transfersheet fed from the selected paper feed tray, at the same speed as thatof the rotation of the photosensitive drum 15, thereby to transfer thetoner image from the photosensitive drum 15 onto one side of thetransfer sheet. A fixing unit 17 thermally fixes this toner image.

[0045] Thereafter, in a one-sided copying mode, a paper discharging unit18 conveys the transfer sheet to the finisher 100 as the post processor.

[0046] When a transfer sheet formed with a toner image on one side ofthe sheet is to be inverted in order to face down the sheet to set thesheets in the page order, the paper discharging unit 18 conveys thistransfer sheet to a two-sided paper conveying route 113. An invertingunit 112 inverts the sheet. The inverted sheet is conveyed to thefinisher 100 via the inverted sheet conveyer route 114.

[0047] The finisher receives the transfer sheet having the toner imageformed on its one side, sent from the copying machine main body. Abranch deflection plate 101 of the finisher 100 selectively guides thetransfer sheet to a stacker conveyer roller (i.e., normal paperdischarging roller) 102 or a stapler conveyer roller 105.

[0048] In other words, when the branch deflection plate 101 is switchedto face upward, the transfer sheet from the copying machine main bodycan be discharged to a stacker tray (i.e., normal paper discharge tray)104 via the stacker conveyer roller 102 and a stacker paper dischargeroller 103.

[0049] The stacker tray 104 is a paper discharge tray that can be movedforward and backward. The stacker tray 104 moves forward and backwardfor each document or for each copy sorted by using the MEM-C 205 or theHDD 207, and easily sorts the discharged transfer (i.e., copy) sheets.

[0050] When the branch deflection plate 101 is switched to facedownward, a one-side copied transfer sheet sent from the copying machinemain body can be discharged to a staple tray 108 via a stapler conveyerroller 105 and a stapler paper discharge roller 107.

[0051] Each time when one sheet of transfer paper is discharged to thestaple tray 108, an edge aligning jogger (i.e., drop stopper) 109 alignsthe sheet. A stapler 106 staples one set of copied paper. The transfersheets stapled by the stapler 106 drop onto a stapled-paper dischargetray (i.e. drop tray) 110 based on the own weight of the paper, and areaccommodated on this tray.

[0052] On the other hand, in a two-sided copying mode, the paperdischarging unit 18 conveys a one-side copied transfer sheet (having atoner image formed on one side thereof to the two-sided paper conveyingroute 113. The inverting unit 112 inverts the sheet with a switchbackmethod. The inverted sheet is conveyed to a two-sided paper conveyerunit 111.

[0053] The two-sided paper conveyer unit 111 feeds the received transfersheet, and the longitudinal conveyer unit 14 conveys the transfer sheetagain to a position where the sheet is in contact with thephotosensitive drum 15. The toner image formed on the photosensitivedrum 15 is transferred onto the other side of the paper. The fixing unit17 fixes this toner image. The paper discharging unit 18 conveys thetransfer sheet to the finisher 100. Thereafter, operation similar tothat explained above is carried out.

[0054] A main motor (not shown) drives the photosensitive drum 15, theconveyer belt 16, the fixing unit 17, the paper discharging unit 18, andthe developing unit 27. Paper feed clutches transmit the driving of themain motor to the corresponding paper feeders 11 to 13 respectively todrive these feeders. An intermediate clutch transmits the driving of themain motor to the longitudinal conveyer unit 14 to drive this unit. Theimage forming section including the writing unit 57 constitutes theblock 80 shown in FIG. 1.

[0055]FIG. 3 is a layout view of the operation panel 30 that is providedin the main body of the digital copying machines.

[0056] The operation section 30 comprises a liquid-crystal touch panel31, a ten-key 32, a clear/stop key 33, a print key 34, a clear modes key35, and an initialize key 36.

[0057] The liquid-crystal touch panel 31 comprises a touch panel on thesurface of a liquid crystal display, and can display messages about eachfunction key, a number of sheets, a machine condition, etc.

[0058] The ten-key 32 is used to input a number of printing sheets, amagnification, etc.

[0059] The clear/stop key 33 is used to clear a numeric (i.e., copynumber), or stop the operation currently carried out (i.e., reading orprinting operation).

[0060] The print key 34 is used to instruct a starting of a copyoperation.

[0061] The clear modes key 35 is used to clear all contents of a setmode.

[0062] The initialize key 36 is used to optionally customize aninitialization state of the machine. In the present embodiment, the userpresses the initialize key 36 to display an initialization menu screenon the liquid-crystal touch panel 31.

[0063]FIG. 4 is an illustration of one example of an operation panelscreen displayed on the liquid crystal touch panel 31 when a powersource is turned on.

[0064] When the user touches any one of function keys of an operationscreen displayed on the liquid-crystal touch panel 31, a function (i.e.,mode) displayed within a frame of the function key is selected. Then, awhite-and-black display is inverted, as indicated by a shaded portion inFIG. 4.

[0065] When the user touches the function key, an operation screen forsetting a detailed function including a magnification, for example, isdisplayed, when the setting of the magnification is necessary.

[0066] As the liquid-crystal touch panel 31 uses a dot display unit,this touch panel can make an optimum graphical display.

[0067] A message area for displaying a message such as “Ready forcopying” or “Please wait” is provided at a left upper side of theoperation screen shown in FIG. 4. A copying number display section thatdisplays a set number of copying sheets is provided at a right upperside of the operation screen. An auto image density key [Auto ImageDensity] to assign an automatic adjustment of image concentration isdisplayed below the copying number display section. An auto paper selectkey [Auto Paper Select] to assign an automatic selection of a transfersheet is displayed below the auto image density key. A full size key[Full Size] to assign a full size of copy is displayed below theautomatic sheet-selecting key.

[0068] A sort key [Sort] to assign an arrangement of each set of copiedsheets of paper in a page order is displayed at a right side in a secondrow from the bottom. A stack key [Stack] to assign a sorting of copiedsheets of paper for each page is displayed next to the sort key in thesame row. A staple key [Staple] to assign a stapling of sorted sheets ofpaper for each set is displayed next to the stack key in the same row.

[0069] A reduce/enlarge key [Reduce/Enlarge] to assign expansion orcompression as copy magnification is displayed at a right side of thebottom row. A duplex/division key [Duplex/Division] to assign atwo-sided copying mode or a division mode is displayed next to thereduce/enlarge key. A number up key [Number Up] to set a number up copymode is displayed next to the duplex/division key in the same row.Further, a tandem mode key [Tandem] is displayed next to the number upkey in the same row. This key is used to set a tandem mode to carry outa tandem operation of reading or copying to be described later, bysimultaneously starting a plurality of digital copying machines that areconnected via a communication line.

[0070] Keys of a selected mode are displayed in a mesh. When the tandemmode is not selected by the tandem key [Tandem], a single mode forexecuting a normal copy operation is set. Operation in the tandem modewill be explained in detail later.

[0071] The operation from when the scanner 50 reads an image from thedocument till when an electrostatic latent image corresponding to theimage data is formed on the surface of the photosensitive drum 15 willbe explained with reference to FIG. 2. The electrostatic latent imagerefers to a potential distribution that is generated on the surface ofthe photosensitive drum 15 (i.e., surface charged by the charger) when alaser beam is emitted onto this surface to write the image data.

[0072] The scanner 50 consists of the exposure glass 6 on which thedocument is mounted, and an optical scanning system. The opticalscanning system consists of an exposure lamp 51, a first mirror 52, alens 53, and a charge coupled device (CCD) image sensor 54.

[0073] The exposure lamp 51 and the first mirror 52 are fixed to a firstcarriage (not shown), and a second mirror 55 and a third mirror 56 arefixed to a second carriage (not shown).

[0074] To read an image from the document, the first carriage and thesecond carriage are mechanically scanned at a relative speed of two toone so as not to change an optical path length.

[0075] A driving section including a scanner drive motor (not shown)drives the optical scanning system.

[0076] The scanner 50 optically reads the image data from the document,and converts the image into an electric signal. In other words, theexposure lamp 51 of the optical scanning system irradiates the imagesurface on the document. The CCD image sensor 54 receives an opticalimage reflected from the image surface, and forms an image onto thelight reception surface of the CCD image sensor 54 via the first mirror52, the second mirror 55, the third mirror 56, and the lens 53. The CCDimage sensor 54 converts the formed image into an electric signal.

[0077] The lens 53 and the CCD image sensor 54 are moved to the left andright directions in the configuration shown in FIG. 2, thereby to changethe image reading magnification in the document feeding direction. Inother words, positions of the lens 53 and the CCD image sensor 54 in theleft and right directions are set corresponding to the copymagnification set in advance.

[0078] The writing unit 57 of the plotter 80 consists of a laser outputunit 58, an image condensing lens 59, and a mirror 60. The laser outputunit 58 has in its inside a laser diode as a laser beam source, and apolygon mirror that is rotated at a high constant speed by the motor.

[0079] The polygon mirror that is rotated at a constant speed deflectsthe laser beam emitted from the laser output unit 58. The deflectedlaser beam passes through the condensing lens 59. The mirror 60 reflectsthe laser beam. The beam is focused to form an image onto the chargedsurface of the photosensitive drum 15.

[0080] In other words, the laser beam deflected by the polygon mirrorscans the photosensitive drum 15 in a direction orthogonal with therotation direction of the photosensitive drum 15. The laser beam formsan image signal in lines based on the image data output from the imageprocessor (not shown) within the engine application specific integratedcircuit (ASIC) 301 shown in FIG. 1. By repeating a main scanning at apredetermined cycle corresponding to the rotation speed of thephotosensitive drum 15 and the scanning density or a recording density,an electrostatic latent image is formed on the charged surface of thephotosensitive drum 15.

[0081] A synchronization detector (not shown) detects a laser beamimmediately before scanning the photosensitive drum 15. A laser writingcontroller (not shown) within the plotter 80 generates a control signalto input and output a laser diode turn-on start timing and image datafor each scanning, by using a main scanning synchronization signaloutput from the synchronization detector.

[0082]FIG. 1 is a block diagram of a configuration example of a controlsystem for this digital copying machine.

[0083] This digital copying machine has a controller 200, an engine 300,and an Institute of Electrical and Electronic Engineers (IEEE) 1394interface (I/F) 400 that are connected to each other via a peripheralcomponent interconnect (PCI) bus 500.

[0084] The controller 200 controls the whole of the digital copyingmachine including the control of input from a drawing, communication,and operation section 30. The controller 200 comprises a centralprocessing unit (CPU) 201, a north bridge (NB) 202, a plotter memory(MEM-P) 203, a south bridge (SB) 204, an MEM-C 205, a controllerapplication specific integrated circuit (ASIC) 206, and an HDD 207. TheNB 202 and the controller ASIC 206 are connected to each other via anaccelerated graphics port (AGP) bus 208. The NB 202 and the SB 204 areconnected to each other via a PCI bus 209.

[0085] The CPU 201 is a microcomputer that collectively controls thewhole of the controller 200, and consists of a central processing unit,a program ROM, and RAM.

[0086] The NB 202 connects the CPU 201, the MEM-P 203, the SB 204, andthe AGP bus 208 to each other.

[0087] The MEM-P 203 is a plotter memory (i.e., drawing memory) that isused to develop the image data to be transferred to the plotter 80during a printing.

[0088] The SB 204 connects the NB 202, and a PCI device, and aperipheral device (not shown), to each other.

[0089] The MEM-C 205 is a scanner memory that temporarily stores theimage data read by the scanner 50 during a scanning (i.e., reading) orcopying operation.

[0090] The controller ASIC 206 is an image processing integrated circuithaving an image processing hardware element including an editing unitand a compression and expansion unit. The controller ASIC 206 also has arole of a bridge that connects between the AGP bus 208, the PCI bus 500,the HDD 207, and the MEM-C 205.

[0091] The editing unit has a function of carrying out an editprocessing such as a change of magnification of image data read by thescanner 50 or image data to be transferred to the plotter 80.

[0092] The compression and expansion unit has a function of a compressorthat compresses (i.e., encodes) normal image data, and an expander thatexpands (i.e., decodes) the compressed image data.

[0093] The HDD 207 is a storage that stores various kinds of data suchas a large amount of image data, hysteresis data, and programs includinga program relating to the present invention. The HDD 207, the MEM-P 203,and the MEM-C 205 all correspond to the image storage. A large capacitystorage such as an optical disk can also be used instead of the HDD 207.

[0094] The AGP bus 208 is a bus interface for a graphics acceleratorcard that is proposed to speed up the graphic processing. The AGP bus208 makes it possible to directly access the MEM-P 203 at a highthroughput to speed up the graphics accelerator card.

[0095] The AGP bus 208 is originally used to smoothly display athree-dimensional image. In the present digital copying machine, the NB202 and the controller ASIC 206 are connected together via the AGP bus208. When the NB 202 and the controller ASIC 206 are connected togethervia the PCI bus, performance is lowered. Therefore, the AGP bus 208 isextensively utilized for this purpose.

[0096] The engine 300 includes the engine ASI 301 including an imageprocessing section that carries out image processing such as errordiffusion and gamma conversion, and a PCI section, in addition to theengine parts such as the scanner 50 and the plotter 80 as describedabove.

[0097] An IEEE13941/F400 is an external communication unit thatcommunicates with other digital copying machines via a communicationline, when the tandem mode is set in a state that these other digitalcopying machines are connected (i.e., in tandem) via a communicationline of the IEEE13941 standard as a general-purpose communication line(hereinafter, “communication line”). It is also possible to use an I/Fother than the IEEE13941/F400. In this case, the other digital copyingmachines need to be connected via the I/F communication line.

[0098] The CPU 201 operates according to a program relating to thepresent invention that is stored in the HDD 207, thereby to achieve thefunctions of the present invention. In other words, the CPU 201 achievesthe functions of an external read controller (including a compressioncontroller), an external image forming controller (including anexpansion controller), a parallel read controller (including acompression controller, an area securer, a first memory controller, anda second memory controller), a parallel image forming controller(including an expansion controller), and a memory management modesetter, respectively.

[0099]FIG. 5 is an illustration of one example of an image formingsystem having a plurality of the digital copying machinees connectedtogether.

[0100] Four digital copying machines 601 to 604 are connected to eachother via a communication line 607 of the IEEE1394 standard that makesit possible to transfer image data at a high speed. The communicationline 607 has a limit to the length of the cable. Therefore, when thereis a distance between the four digital copying machines 601 to 604,repeaters 610 are inserted into between the copying machines toextensively connect between these copying machines.

[0101] When the user operates the key on the operation section 30 of anyone of the four digital copying machines 601 to 604 to instruct asetting of the tandem mode, the CPU 201 of this selected digital copyingmachine sets the tandem mode. The CPU 201 sets the own copying machineas a parent machine, and sets the other three digital copying machinesas child machines.

[0102]FIG. 5 is an illustration of a state that, based on the keyoperation on the operation section 30 of the digital copying machine601, the CPU 301 of this machine sets the following. The CPU 301 setsthe tandem mode, sets the own machine as a parent machine, and sets thedigital copying machines 602 to 604 as child machines.

[0103] Each of the parent machine and the child machines has the ADF 1shown in FIG. 2. A large number of sheets of original document aremounted in uniform division onto the document tray 2 of the parentmachine and onto the document tray 2 of the ADF 1 of at least one childmachine. With this arrangement, a large number of images of the documentcan be read at a high speed of at least two times the copying speed ofone digital copying machine. In many cases, an electronic sort mode orthe like is used to copy the large .number of sheets of originaldocument. In the electronic sort mode, a large number of sheets oforiginal document are sequentially read and stored in the image memory.All images on the sheets of original document are printed out ontosheets of paper for each set in the order of pages. A plurality of setsof copied sheets of paper are arranged in the order of pages.

[0104] The image data read by the scanner 50 of at least one childmachine is transferred to the parent digital copying machine 601. Whenthe image data are collectively stored in the MEM-C 205 or the HDD 207,the subsequent processing becomes simple.

[0105] When the image data read by the scanner 50 of at least one childmachine is stored in the MEM-C 205 or the HDD 207 of this child machine,it becomes necessary to embed image data to print out one set of copy inpage order. From this viewpoint, it is preferable that the image dataread by the scanner 50 of the child machine are collectively stored inthe MEM-C 205 or the HDD 207 of the parent machine.

[0106] Processing of the digital copying machines 601 to 604 thatconstitute the image forming system according to the embodiments of thepresent invention will be explained in detail below with reference toFIG. 6 and subsequent drawings. The digital copying machine 601 will beregarded as a parent machine for explanation.

[0107] The processing of the digital copying machines 601 to 604according to the first embodiment of the present invention will beexplained with reference to FIG. 6 to FIG. 8.

[0108]FIG. 6 is a flowchart of one example of the processing of thecontrollers 200 of the digital copying machines 601 to 604 according tothe present invention.

[0109]FIG. 7 and FIG. 8 are illustrations of one example of a flow ofnormal image data that is not compressed when the digital copyingmachines 601 to 604 read images from a document.

[0110] When the user presses the tandem key on the operation section 30of the digital copying machine 601 to instruct the setting of the tandemmode, the CPU 201 within the controller 200 of this machine 601 sets thetandem mode. The CPU 201 sets the own machine as the parent machine, andsets the other digital copying machines as child machines.

[0111] The CPU 201 checks the states of the other digital copyingmachines.

[0112] The CPU 201 transmits a predetermined state confirmation signalto the communication line 607 via the IEEE13941/F400 of the own machine.

[0113] When the power source is ON and also when communication ispossible, the CPU 201 of each of the digital copying machines 602 to 604receives the state confirmation signal from the digital copying machine601 via the IEEE13941/F400 of the own machine. The CPU 201 checks thestates of the scanner 50 and the plotter 80 of the own machine. The CPU201 transmits a state result signal indicating a check result togetherwith a device code of the own machine, to the transmitter digitalcopying machine 601 via the IEEE13941/F400 of the own machine.

[0114] The CPU 201 of the digital copying machine 601 receives the checkresult together with a device code. The CPU 201 displays the device codeand the states of the scanner 50 and the plotter 80 indicated by thestate result signal, on the liquid crystal touch panel 31 of theoperation section 30. The user reads this display.

[0115] The user of the digital copying machine 601 confirms whetherthere is any other digital copying machine that can copy in the tandemmode, based on the display contents on the liquid crystal touch panel 31of the operation section 30 (step S1 in FIG. 6). When there is nodigital copying machine that can copy, the user operates the key on theoperation section 30 to instruct a change of the setting to the singlemode. At the same time, the user operates the ten-key 32 on theoperation section 30 to input a copying number of sheets. When only onecopy is to be made, the input of a numeral “1” is not necessary.

[0116] The user sets one sheet of original document on the exposureglass 6 of the scanner 50, and presses the print key (i.e., start key)34. Alternatively, the user sets one or more sheets of original documenton the document tray 2 of the ADF 1, and presses the print key 34.

[0117] When the tandem mode is set and also when there is theinstruction to change the setting to the single mode, the CPU 201 of thedigital copying machine 601 changes the setting of the mode to thesingle mode.

[0118] When the copying number of sheets is input, the CPU 201 sets thecopying number of sheets.

[0119] When the user presses the print key 34 on the operation section30 in the state that the single mode is set, the digital copying machine601 carries out a normal copying (step S13).

[0120] In other words, when the document is set on the exposure glass 6of the scanner 50 of the own machine, the CPU 201 makes this scanner 50read the image from the document. The CPU 201 makes the image stored inthe MEM-C 205 or the HDD 207 of the own machine via the engine ASIC 301,the PCI bus 500, and the controller ASIC 206 as shown in FIG. 7 or FIG.8. Thereafter, the CPU 201 makes the scanner read the image data of thedocument stored in the MEM-C 205 or the HDD 207, transfers the imagedata to the plotter 80 of the own machine via the controller ASIC 206,the PCI bus 500, and the engine ASIC 301. The CPU 201 makes the plotter80 print out the image to form the image. When the user sets “2” or alarger set number, the CPU 201 makes the scanner 50 read repeatedly thedocument image data stored in the MEM-C 205 or the HDD 207 of the ownmachine, by the set number. The CPU 201 makes the image datasequentially transferred to the plotter 80 of the own machine to printout the image.

[0121] When one or more sheets of original document are set on thedocument tray 2 of the ADF 1 of the own machine, the CPU 201 makes thisADF 1 (not shown in FIG. 1) automatically feed each sheet of originaldocument from the document tray 2. The CPU 201 makes the scanner 50 ofthe own machine sequentially read the images from the sheets of originaldocument. The CPU 201 makes the images stored in the MEM-C 205 or theHDD 207 of the own machine via the engine ASIC 301, the PCI bus 500, andthe controller ASIC 206. Thereafter, the CPU 201 makes the scannersequentially read the image data of the document stored in the MEM-C 205or the HDD 207, transfers the image data to the plotter 80 of the ownmachine via the controller ASIC 206, the PCI bus 500, and the engineASIC 301. The CPU 201 makes the plotter 80 print out the images. Whenthe user sets “2” or a larger number, the CPU 201 makes the scanner 50sequentially read repeatedly the document image data stored in the MEM-C205 or the HDD 207 of the own machine, by the set number. The CPU 201makes the image data sequentially transferred to the plotter 80 of theown machine to print out the images.

[0122] On the other hand, when there is at least any one other digitalcopying machine that can copy in the tandem mode, the user of thedigital copying machine 601 operates the key on the operation section 30to assign one optional machine as a child machine. Even when there is atleast any one other digital copying machine that can copy in the tandemmode, the user may not operate the key on the operation section 30 toassign one optional machine as a child machine.

[0123] When other digital copying machine is not assigned as a childmachine and also when a set number is “1”, the user presses the printkey 34 of the own machine each time when one sheet of original documentis set on the scanner 50 of the own machine. Alternatively, the usersets one or more sheets of original document on the document tray 2 ofthe ADF 1 of the own machine, and presses the print key 34. In thiscase, the CPU 201 of the digital copying machine 601 makes the printercarry out the normal copying at step S13 that is the same as the copyingoperation as described above (at steps S1, S2, S7, and S13).

[0124] When other digital copying machine is assigned as a childmachine, the CPU 201 of the digital copying machine 601 sets the ownmachine as a parent machine, and sets the assigned other digital copyingmachine as a child machine. The IEEE13941/F400 transmits a singleoperation prohibition signal to this child machine to instruct theprohibition of the single operation.

[0125] The child machine receives the single operation prohibitionsignal, and invalidates the key input to the operation section 30 of theown machine, thereby to prohibit the single operation (i.e., normalcopying operation).

[0126] The user sets “2” or a larger number as a set number, and pressesthe print key 34 of the parent machine, each time when one sheet oforiginal document is set to the scanner 50 of the digital copyingmachine 601 as the parent machine. Alternatively, the user sets a sheetor sheets of original document on the document tray 2 of the ADF 1 ofthe parent machine, and presses the print key 34. In this case, the CPU201 carries out the following processing.

[0127] When the document is set on the scanner 50 of the own machine,the CPU 201 of the own machine makes this scanner 50 read the image fromthe document. The CPU 201 makes the image stored in the MEM-C 205 or theHDD 207 of the own machine via the engine ASIC 301, the PCI bus 500, andthe controller ASIC 206 as shown in FIG. 7 or FIG. 8. The CPU 201uniformly allocates the set processing number to the own machine and thechild machines respectively, and instructs an allocation number to eachchild machine. For example, when the set number to the child digitalcopying machines 602 to 604 is “400”, an allocation number “100” isinstructed to each child machine.

[0128] The CPU 201 carries out the following controls in parallel. TheCPU 201 makes the scanner 50 read repeatedly the document image datastored in the MEM-C 205 or the HDD 207 of the own machine, by theallocated number. The CPU 201 makes the IEEE13941/F400 of the ownmachine sequentially transfer the document image data to the plotter 80of the own machine to print out the image (steps S1 to S6).

[0129] When one or more sheets of original document are set on thedocument tray 2 of the ADF 1 of the own machine, the CPU 201 makes thisADF 1 automatically feed each sheet of original document from thedocument tray 2. The CPU 201 makes the scanner 50 of the own machinesequentially read the images from the sheets of original document. TheCPU 201 makes the images stored in the MEM-C 205 or the HDD 207 of theown machine via the engine ASIC 301, the PCI bus 500, and the controllerASIC 206. The CPU 201 uniformly allocates the set processing number tothe own machine and the child machines respectively, and instructs anallocation number to each child machine. Thereafter, the CPU 201 makesthe scanner sequentially read the image data of the document stored inthe MEM-C 205 or the HDD 207 of the own machine. The CPU carries out thefollowing control in parallel. The CPU 201 makes the image datatransferred to the plotter 80 of the own machine via the controller ASIC206, the PCI bus 500, and the engine ASIC 301 of the own machine, andmakes the plotter 80 print out the images. The CPU 201 makes theIEEE13941/F400 of the own machine sequentially transfer the documentimage data to the plotter 80 of the own machine to print out the image(steps S1 to S6).

[0130] When the document is set to the scanner 50 of the child machineduring a period while this scanner 50 is reading the document image,this effect is notified to the own machine from the child machine.Therefore, after the own machine reads the document image, the CPU 201makes the scanner 50 of the child machine read the image from thedocument set to the scanner 50. The CPU 201 makes the IEEE13941/F400 ofthe child machine transfer the document image data to the own machine,and makes the image data stored in the MEM-C 205 or the HDD 207 of theown machine. When the document is set to the document tray 2 of the ADF1 of the child machine during a period while this scanner 50 of the ownmachine is reading the document image, this effect is notified to theown machine from the child machine. After the own machine reads thedocument image, the CPU 201 makes the ADF 1 automatically feed eachsheet of original document from the document tray 2 to the scanner 50.The CPU 201 makes the scanner 50 of the child machine read the images ofthe document set to this scanner 50. The CPU 201 makes theIEEE13941/F400 of the child machine sequentially transfer the documentimage data to the own machine, and makes the image data stored in theMEM-C 205 or the HDD 207 of the own machine.

[0131] When the user presses the print key 34 in a sate that thedocument is set to only the scanner 50 of the child machine, the CPU 201makes the scanner 50 of the child machine read the image from thedocument set to the scanner 50. The CPU 201 makes the IEEE13941/F400 ofthe child machine transfer the document image data to the own machine,and makes the image data stored in the MEM-C 205 or the HDD 207 of theown machine. When the user presses the print key 34 in a sate that thedocument is set to only the document tray 2 of the ADF 1 of the childmachine, the CPU 201 makes the ADF 1 automatically feed each sheet oforiginal document from the document tray 2 to scanner 50 of the childmachine. The CPU 201 makes the scanner 50 of the child machine read theimages of the document. The CPU 201 makes the IEEE13941/F400 of thechild machine transfer the document image data to the own machine, andmakes the image data stored in the MEM-C 205 or the HDD 207 of the ownmachine.

[0132] The user sets “2” or a larger number as a set number, and pressesthe print key 34 of the parent machine, each time when one sheet oforiginal document is set to the scanner 50 of the parent machine and thescanner 50 of the child machine respectively. Alternatively, the usersets two or more sheets of original document by allocation onto thedocument tray 2 of the ADF 1 of the parent machine and the document tray2 of the ADF 1 of the child machine respectively, and presses the printkey 34. In this case, the CPU 201 carries out the following processing.

[0133] When the document is set on the scanner 50 of the own machine andthe scanner 50 of the child machine respectively, the CPU 201 of the ownmachine makes the scanner 50 of the own machine read the set image fromthe document. The CPU 201 makes the image stored in the MEM-C 205 or theHDD 207 of the own machine via the engine ASIC 301, the PCI bus 500, andthe controller ASIC 206 as shown in FIG. 7 or FIG. 8. At the same time,the CPU 201 of the child machine makes the scanner 50 of the childmachine read the set image from the document. The CPU 201 makes theIEEE13941/F400 of the child machine transfer the document image data tothe own machine, and makes the image data stored in the MEM-C 205 or theHDD 207 of the own machine (at steps S1, S2, and S7 to S12). The CPU 201carries out the following controls in parallel. When the originaldocument is set on the document tray 2 of the ADF 1 of the own machineand on the document tray 2 of the ADF 1 of the child machinerespectively, the CPU 201 makes the ADF 1 of the own machineautomatically feed each of original document from the document tray 2,and makes the scanners 50 of the own machine sequentially read theimages from the document respectively. The CPU 201 makes the imagesstored into the MEM-C 205 or the HDD 207 of the own machine via theengine ASIC 301, the PCI bus 500, and the controller ASIC 206 as shownin FIG. 7 or FIG. 8. At the same time, the CPU 201 makes the ADF 1 ofthe child machine automatically feed each sheet of original documentfrom the document tray 2, and makes the scanner 50 of the child machinesequentially read the images from the document. The CPU 201 makes theIEEE13941/F400 of the child machine sequentially transfer the image datato the own machine, and makes the images stored into the MEM-C 205 orthe HDD 207 of the own machine (at steps S1, S2, and S7 to S12).

[0134] Thereafter, the CPU 201 instructs a uniform allocation of the setnumber to the own machine and the child machine respectively, andinstructs the allocation number to the child machine.

[0135] The CPU 201 carries out the following controls in parallel. TheCPU 201 makes the scanner 50 read repeatedly the document image datastored in the MEM-C 205 or the HDD 207 of the own machine, by theallocated number. The CPU 201 makes the image data transferred to theplotter 80 of the own machine via the controller ASIC 206, the PCI bus500, and the engine ASIC 301 of the own machine, and makes the plotter80 print out the images. The CPU 201 makes the IEEE13941/F400 of the ownmachine sequentially transfer the read document image data to theplotter 80 of the child machine as well to print out the image (the samesteps S4 to S6).

[0136] In order to make the MEM-C 205 or the HDD 207 of the own machinestore the image data, it is checked whether the memory management modefor managing the MEM-C 205 or the HDD 207 of the own machine is set. TheCPU 201 selects a memory control of the image data based on a result ofthis check (at steps S10 to S12). This processing will be explained indetail later. The user can set the memory management mode in advance byoperating the key on the operation section 30.

[0137] When the user sets “2” or a larger number as a set number underthe setting of the tandem mode, the image data stored in the MEM-C 205or the HDD 207 of the own machine can be repeatedly read outsequentially by the set number. The image data can be sequentiallytransferred to the plotter 80 of the own machine via the controller ASIC206, the PCI bus 500, and the engine ASIC 301 of the own machine,thereby to make the plotter 80 of the own machine print out the images.Alternatively, the image data stored in the MEM-C 205 or the HDD 207 ofthe own machine can be repeatedly read out sequentially by the setnumber. The IEEE13941/F400 of the own machine can be made tosequentially transfer the document image data to the plotter 80 of thechild machine to print out the images.

[0138] According to the first embodiment, when a number of sheets oforiginal document that are required to be copied exceeds a maximumnumber of sheets that can be mounted on the document tray 2 of the ADF 1of one digital copying machine, the document sheets can be allocated tothe document trays 2 of the ADF 1 of a plurality of digital copyingmachines. The user operates the key to set a required copy number on theoperation section 30 according to a need. Last, the user only pressesthe print key 34 to instruct the start of copying. Therefore, the user'swork efficiency can be improved. Further, the copy time can beshortened.

[0139] Alternatively, a part of the document may be set to the documenttray 2 of the ADF 1 of one digital copying machine. The user operatesthe key to set a required copy number on the operation section 30according to a need. After pressing the print key 34, the user can setthe rest of document to the document tray 2 of the ADF 1 of otherdigital copying machines. With this arrangement, all the document sheetscan be read continuously. Therefore, the user's work efficiency can beimproved.

[0140] When the ADF 1 cannot be used, such as when the ADF 1 is introuble or is not mounted, for example, one sheet of a large documentcan be set to each scanner 50 of each of a plurality of digital copyingmachines. The user operates the key to set a required copy number on theoperation section 30 according to a need. Last, the user only pressesthe print key 34 to instruct the start of copying until when all thedocument sheets are read out. Therefore, the user's work efficiency canbe improved more than that when only one digital copying machine isused. Further, the copy time can be shortened.

[0141] In the first embodiment, the document image data read by thescanner 50 of the own or child machine is stored in the MEM-C 205 or theHDD 207 of the own machine. However, when the memory capacity of theMEM-C 205 is not large, the image data can be stored in the HDD 207. Inthis case, the image data is once stored in the MEM-C 205, and is thentransferred to the HDD 207 to store the data. When the image data isstored in the HDD 207 instead of the MEM-C 205, the capacity of theMEM-C 205 used can be minimized. This has also an advantage in that theimage data once stored in the HDD 207 is not erased even when the powersource is off.

[0142] The processing of the digital copying machines 601 to 604according to the second embodiment of the present invention will beexplained with reference to FIG. 9 and FIG. 10.

[0143]FIG. 9 and FIG. 10 are illustrations of different examples of aflow of image data that is compressed when the digital copying machines601 to 604 read images from a document.

[0144] The second embodiment is different from the first embodiment inthat controls of the CPU 201 of the parent digital copying machine 601are different in points (1) and (2) described below. (1) The documentimage data read by the scanner 50 of the own or child machine is storedin the MEM-C 205 or the HDD 207 of the own machine as follows. As shownin FIG. 9 or FIG. 10, the compression and expansion unit within thecontroller ASIC 206 compresses the image data. The own or child machinemakes the plotter 80 print out the image as follows. The compressedimage data stored in the MEM-C 205 or the HDD 207 of the own machine isread out. Then, the compression and expansion unit within the controllerASIC 206 expands the image data to restore the original image data.

[0145] The document image data read by the scanner 50 of the own orchild machine is stored in the HDD 207 of the own machine as follows. Asshown in FIG. 10, the compression and expansion unit within thecontroller ASIC 206 compresses the image data. The compressed image datais once stored in the MEM-C 205 of the own machine, and is then storedin the HDD 207 of the own machine. The own or child machine makes theplotter 80 print out the image as follows. The compressed image datastored in the HDD 207 of the own machine is read out, and is then oncestored in the MEM-C 205 of the own machine. The image data istransferred to the controller ASIC 206. The compression and expansionunit within the controller ASIC 206 expands the image data.

[0146] (2) The document image data read by the scanner 50 of the own orchild machine is stored in the MEM-C 205 or the HDD 207 of the ownmachine as follows. As shown in FIG. 9 or FIG. 10, the compression andexpansion unit within the controller ASIC 206 compresses the image data.The compressed image data stored in the MEM-C 205 or the HDD 207 of theown machine is read out. The compression and expansion unit within thecontroller ASIC 206 of the own machine expands the image data that istransferred to the plotter 80 of the own machine. However, thecompression and expansion unit within the controller ASIC 206 of thechild machine does not expand the image data that is transferred to thechild machine. In other words, the compressed image data is transferredto the child machine. Then, the compression and expansion unit withinthe controller ASIC 206 of the child machine expands the image data.

[0147] The document image data read by the scanner 50 of the own orchild machine is stored in the HDD 207 of the own machine as follows. Asshown in FIG. 10, the compression and expansion unit within thecontroller ASIC 206 compresses the image data. The compressed image datais once stored in the MEM-C 205 of the own machine, and is then storedin the HDD 207 of the own machine. The own or child machine makes theplotter 80 print out the image as follows. The compressed image datastored in the HDD 207 of the own machine is read out, and is then oncestored in the MEM-C 205 of the own machine. The image data istransferred to the controller ASIC 206. The compression and expansionunit within the controller ASIC 206 of the own machine expands the imagedata that is transferred to the plotter 80 of the own machine. Thecompressed image data to be transferred to the child machine istransferred straight to the child machine. Then, the compression andexpansion unit within the controller ASIC 206 of the child machineexpands the image data. In other words, the child machine receives thecompressed image data from the parent machine, and transfers this datato the controller ASIC 206 of the own machine. The compression andexpansion unit within this controller ASIC 206 expands the image data,and once stores the expanded image data into the MEM-C 205 of the ownmachine. The expanded image data is transferred to the plotter 80 of theown machine to print out the image.

[0148] According to the processing explained in (1) and (2) above, theimage data stored in the MEM-C 205 or the HDD 207 of the own machine iscompressed. Therefore, the capacity of these memories used can beminimized, which can also improve the data transfer speed.

[0149] The processing of the digital copying machines 601 to 604according to the third embodiment of the present invention will beexplained with reference to FIG. 11.

[0150]FIG. 11 is an explanatory diagram of a memory control of imagedata to the MEM-C 205 or the HDD 207 in the digital copying machineshown in FIG. 1.

[0151] The third embodiment is substantially the same as the first andsecond embodiments. In the first and second embodiments, the explanationof the memory control of the image data to the MEM-C 205 or the HDD 207in the digital copying machines 601 to 604 respectively is omitted.Therefore, this memory control will be explained in the thirdembodiment. For convenience, the explanation of the compression andexpansion of the image data will be omitted.

[0152] The user presses the key on the operation section 30 of the ownmachine, to set the own machine as a parent machine, and set the otherdigital copying machines 601 to 604 as child machines respectively. Theuser presses the print key 34 in a state that a large number of sheetsof original document are uniformly allocated to the document tray 2 ofthe ADF 1 of the own machine and the document trays 2 of the ADF 1 ofchild machines A, B, and C (corresponding to the other digital copyingmachines 602, 603, and 604). Then, the CPU 201 of the digital copyingmachine 601 makes the ADF 1 of the own machine automatically feed eachsheet of original document from the document tray 2, and makes thescanner 50 of the own machine sequentially read the image from thedocument. The CPU 201 makes the image stored into an optional unusedmemory area of the MEM-C 205 or the HDD 207 of the own machine via theengine ASIC 301, the PCI bus 500, and the controller ASIC 206 as shownin FIG. 7 or FIG. 8. At the same time, the CPU 201 makes the ADF 1 ofthe child machine automatically feed each sheet of original documentfrom the document tray 2, and makes the scanners 50 of the childmachines A, B, and C sequentially read the images from the documentrespectively. The CPU 201 makes the IEEE13941/F400 of the child machinessequentially transfer the document image data to the own machine, andmakes the images stored into an optional memory area of the MEM-C 205 orthe HDD 207 of the own machine (at steps S1, S2, and S7 to S12).

[0153] The CPU 201 of the parent machine makes each image data of thedocument read by the scanner 50 of the own machine stored into anoptional unused memory area of the MEM-C 205 or the HDD 207 of the ownmachine, as shown in FIG. 11A. The CPUs 201 of the child machines A, B,and C make each image data of the document read by the scanner 50 of theown machine temporarily stored into an optional memory area of the MEM-C205 or the HDD 207 of the own machine, as shown in FIGS. 11B, 11C, and11D respectively, for example. The CPU 201 makes the IEEE13941/F400 ofthe own machine sequentially transfer the stored images to the parentmachine.

[0154] The processing of the digital copying machines 601 to 604according to the fourth embodiment of the present invention will beexplained with reference to FIG. 12.

[0155]FIG. 12 and FIG. 13 are explanatory diagrams of different memorycontrols of image data to the MEM-C 205 or the HDD 207 when the memorymanagement mode is set in the digital copying machine set as a parentmachine among the digital copying machines 601 to 604. The digitalcopying machine 601 set as the parent machine.

[0156] The fourth embodiment is substantially the same as the first tothird embodiments. In the first to third embodiments, the memory controlof the image data to the MEM-C 205 or the HDD 207 of the own machinethat the CPU 201 of the parent machine carries out corresponding to thepresence or absence of the setting of the memory management mode is notexplained in detail. Therefore, in the fourth embodiment, the memorycontrol will be explained in detail. For convenience, the explanation ofthe compression and expansion of the image data will be omitted.

[0157] The user presses the key on the operation section 30 of the ownmachine, to set the own machine as a parent machine, and set the otherdigital copying machines 601 to 604 as child machines respectively. Atthe same time, the user sets the memory management mode. Then, the CPU201 of the digital copying machine 601 secures a memory area in advanceto continuously store into the MEM-C 205 or the HDD 207 of the ownmachine, the image data read by the scanner 50 of the own machine andthe image data read by the scanners 50 of the child machines A, B, and C(corresponding to the other digital copying machines 602, 603, and 604)respectively in the order of pages of the document.

[0158] The user of the parent machine sets pages 1 to 100 of thedocument to the document tray 2 of the ADF 1 of the parent machine, setspages 101 to 200 of the document to the document tray 2 of the ADF 1 ofthe child machine B, sets pages 201 to 300 of the document to thedocument tray 2 of the ADF 1 of the child machine C, and sets pages 301to 400 of the document to the document tray 2 of the ADF 1 of the childmachine D, respectively, for example. The user of the own machinepresses the key on the operation section 30 to input these pieces ofinformation. Then, the CPU 201 of the parent machine stores the inputinformation as a data table into a predetermined memory area of theMEM-C 205 or the HDD 207 of the own machine, and registers theinformation.

[0159] The user presses the print key 34 in a state that a large numberof sheets of original document (for example, pages 1 to 400) areuniformly allocated to the document tray 2 of the ADF 1 of the ownmachine and the document trays 2 of the ADFs 1 of child machines A, B,and C respectively. Then, the CPU 201 of the digital copying machine 601makes the ADF 1 of the own machine automatically feed each sheet oforiginal document from the document tray 2, and makes the scanner 50 ofthe own machine sequentially read the image from the document. The CPU201 makes the images stored in page order from the header address, intoa memory area secured in advance of the MEM-C 205 or the HDD 207 of theown machine via the engine ASIC 301, the PCI bus 500, and the controllerASIC 206 as shown in FIG. 7 or FIG. 8. At the same time, the CPU 201makes the ADF 1 of the child machine automatically feed each sheet oforiginal document from the document tray 2, and makes the scanners 50 ofchild machines A, B, and C sequentially read the images from thedocument respectively. The CPU 201 makes the IEEE13941/F400 of the childmachines A, B, and C sequentially transfer the document image data tothe own machine. The CPU 201 makes the images stored in page order intoa remaining area the memory area secured in advance of the MEM-C 205 orthe HDD 207 of the own machine (at steps S1, S2, and S7 to S12).

[0160] The CPU 201 of the parent machine makes each image data of thedocument read by the scanner 50 of the own machine stored in page orderfrom the header address, into a memory area secured in advance of theMEM-C 205 or the HDD 207 of the own machine, as shown in FIG. 13. TheCPUs 201 of the child machines A, B, and C make each image data of thedocument read by the scanners 50 of the own machines temporarily storedin page order into an optional memory area of the MEM-C 205 or the HDD207 of the own machines, as shown in FIGS. 11B, 11C, and 11Drespectively, for example. When the scanners 50 of the own machines endreading the images from the document, the CPUs 201 make theIEEE13941/F400 of the own machine sequentially notify the end of thereading to the parent machine.

[0161] When the scanner 50 of the own machine ends reading the imagesfrom the pages 1 to 100 of the document and also when the parent machinereceives the notification of the end of reading from the child machinesA, B, and C respectively, the CPU 201 of the parent machine judges thatall the images are read from the document. The CPU 201 determines anorder of transmitting an image transfer instruction to the childmachines A, B, and C, by referring to the data table. The CPU 201 makesthe IEEE13941/F400 of the own machine transmit the image transferinstruction to the child machines A, B, and C in this order.

[0162] The CPUs 201 of the child machines A, B, and C receive the imagetransfer instruction transmitted from the parent machine, and make theIEEE13941/F400 of the own machine transfer in page order the image dataof the document stored in the MEM-C 205 or the HDD 207 of the ownmachine.

[0163] When all the images of the document are read and also when theorder of transmitting the image transfer instruction is determined, theCPU 201 of the parent machine first makes the IEEE13941/F400 of the ownmachine transmit the image transfer instruction to the child machine A.The child machine A transfers the image data of the document in pageorder from page 101 to 200, to the parent machine. Then, the CPU 201 ofthe parent machine makes the reception data sequentially stored into thememory area secured in advance of the MEM-C 205 or the HDD 207 of theown machine, following the image data of the own (i.e., parent) machine,as shown in FIG. 13.

[0164] The CPU 201 of the parent machine makes the IEEE13941/F400 of theown machine transmit the image transfer instruction to the child machineB. The child machine B transfers the image data of the document in theorder of pages from page 201 to 300, to the parent machine. Then, theCPU 201 of the parent machine makes the reception data sequentiallystored into the memory area secured in advance of the MEM-C 205 or theHDD 207 of the own machine, following the image data of the childmachine A, as shown in FIG. 13.

[0165] Last, the CPU 201 of the parent machine makes the IEEE13941/F400of the own machine transmit the image transfer instruction to the childmachine C. The child machine C transfers the image data of the documentin the order of pages from page 301 to 400, to the parent machine. Then,the CPU 201 of the parent machine makes the reception data sequentiallystored into the memory area secured in advance of the MEM-C 205 or theHDD 207 of the own machine, following the image data of the childmachine B, as shown in FIG. 13.

[0166] On the other hand, when the memory management mode is not set,the user presses the print key 34 in a state that a large number ofsheets of original document are uniformly allocated to the document tray2 of the ADF 1 of the own machine and the document trays 2 of the ADF 1of child machines A, B, and C. Then, the CPU 201 of the parent machinemakes the ADF 1 of the own machine automatically feed each sheet oforiginal document from the document tray 2, and makes the scanner 50 ofthe own machine sequentially read the image from the document. The CPU201 makes each image data stored, in the page order, into an optionalmemory area of the MEM-C 205 or the HDD 207 of the own machine via theengine ASIC 301, the PCI bus 500, and the controller ASIC 206 as shownin FIG. 7 or FIG. 8. At the same time, the CPU 201 makes the ADFs 1 ofthe child machines A, B, and C automatically feed each sheet of originaldocument from the document tray 2, and makes the scanners 50 of thechild machines A, B, and C sequentially read the images from thedocument respectively. The CPU 201 makes the IEEE13941/F400 of the childmachines sequentially transfer the document image data to the ownmachine, and makes the images stored into an optional memory area of theMEM-C 205 or the HDD 207 of the own machine (at steps S1, S2, and S7 toS12).

[0167] The CPU 201 of the parent machine makes each image data of thedocument read by the scanner 50 of the own machine stored in page orderinto an optional memory area of the MEM-C 205 or the HDD 207 of the ownmachine. The CPUs 201 of the child machines A, B, and C make each imagedata of the document read by the scanner 50 of the own machinetemporarily stored into an optional memory area of the MEM-C 205 or theHDD 207 of the own machine, as shown in FIGS. 11B, 11C, and 11Drespectively, for example. The CPU 201 makes the IEEE13941/F400 of theown machine sequentially transfer the stored images to the parentmachine.

[0168] The child machines A, B, and C transfer the image data of thedocument in page order to the parent machine. The CPU 201 of the parentmachine makes the image data sequentially stored into an optional areaof the MEM-C 205 or the HDD 207 of the own machine.

[0169] When the user sets the memory management mode, the CPU 201 of theown machine can secure a memory area for each copying machine in advanceto store into the MEM-C 205 or the HDD 207 of the own machine, the imagedata read by the scanner 50 of the own machine and the image data readby the scanners 50 of the child machines A, B, and C (corresponding tothe other digital copying machines 602, 603, and 604) respectively.

[0170] The user of the parent machine sets pages 1 to 100 of thedocument to the document tray 2 of the ADF 1 of the parent machine, setspages 101 to 200 of the document to the document tray 2 of the ADF 1 ofthe child machine B, sets pages 201 to 300 of the document to thedocument tray 2 of the ADF 1 of the child machine C, and sets pages 301to 400 of the document to the document tray 2 of the ADF 1 of the childmachine D, respectively, for example. The user of the own machinepresses the key on the operation section 30 to input these pieces ofinformation. Then, the CPU 201 of the parent machine stores the inputinformation as a data table into a predetermined memory area of theMEM-C 205 or the HDD 207 of the own machine, and registers theinformation.

[0171] The user presses the print key 34 in a state that a large numberof sheets of original document (for example, pages 1 to 400) areuniformly allocated to the document tray 2 of the ADF 1 of the ownmachine and the document trays 2 of the ADFs 1 of child machines A, B,and C respectively. Then, the CPU 201 of the digital copying machine 601makes the ADF 1 of the own machine automatically feed each sheet oforiginal document from the document tray 2, and makes the scanner 50 ofthe own machine sequentially read the image from the document. The CPU201 makes the scanner 50 of the own machine sequentially read theimages, and makes these images stored in page order into a memory areasecured in advance of the MEM-C 205 or the HDD 207 of the own machinevia the engine ASIC 301, the PCI bus 500, and the controller ASIC 206 asshown in FIG. 7 or FIG. 8. At the same time, the CPU 201 makes the ADFs1 of the child machines A, B, and C automatically feed each sheet oforiginal document from the document tray 2, and makes the scanners 50 ofchild machines A, B, and C sequentially read the images from thedocument respectively. The CPU 201 makes the IEEE13941/F400 of the childmachines A, B, and C sequentially transfer the document image data tothe own machine. The CPU 201 makes the images stored in page order intoa memory area secured in advance of the MEM-C 205 or the HDD 207 of theown machine (at steps S1, S2, and S7 to S12). The CPU 201 of the parentmachine makes each image data of the document read by the scanner 50 ofthe own machine stored in page order into a memory area secured inadvance of the MEM-C 205 or the HDD 207 of the own machine, as shown inFIG. 12A. The CPUs 201 of the child machines A, B, and C make each imagedata of the document read by the scanners 50 of the own machinestemporarily stored in page order into an optional memory area of theMEM-C 205 or the HDD 207 of the own machines, as shown in FIGS. 11B.11C, and 11D respectively. When the scanners 50 of the own machines endreading the images from the document, the CPUs 201 make theIEEE13941/F400 of the own machines sequentially transfer the storedimages to the parent machine.

[0172] The child machines A, B, and C transfer the image data of thedocument in page order to the parent machine. The CPU 201 of the parentmachine makes the image data sequentially stored into an area secured inadvance of the MEM-C 205 or the HDD 207 of the own machine as shown inFIG. 12A.

[0173] Based on the setting of the memory management mode, the CPU 201of the own machine secures a memory area for each copying machine inadvance to store the image data read by the scanner 50 of the ownmachine and the image data read by the scanners 50 of the child machinesA, B, and C into the MEM-C 205 or the HDD 207 of the own machine. Inthis case, the CPU 201 of each child machine can omit the work ofassigning an address each time when transferring the image data to theparent machine. Further, the child machine can continuously transfer theimage data of the document, which has an advantage of being able todeliver image data between the copying machines. However, this also hasa problem of securing a memory area more than is necessary to store theimage data into the MEM-C 205 or the HDD 207. As the memory area to beused is determined at random, there is a risk that a memory area notused between the image data memory area by copying machines becomessmall.

[0174] To avoid the above problems, the following arrangement is made.Based on the setting of the memory management mode, the CPU 201 of thedigital copying machine 601 secures a memory area in advance to storesequentially in page order of the document the image data read by thescanner 50 of the own machine and the image data read by the scanners 50of the child machines A, B, and C into the MEM-C 205 or the HDD 207 ofthe own machine, as shown in FIG. 13. With this arrangement, anexcessive allocation of a memory area for each copying machine can beavoided.

[0175] Further, a memory area not used between the image data memoryarea by copying machines is not prepared as shown in FIG. 12B.Consequently, a used area can be prepared in one large block.

[0176] Further, a large amount of image data can be stored into acontinuous memory area of the MEM-C 205 or the HDD 207. Therefore, theimage data read by the scanner 50 of the own machine and the image dataread by the scanners 50 of the child machines A, B, and C can be storedquickly.

[0177] Further, a large amount of document image data including theimage data read by the scanner 50 of the own machine and the image dataread by the scanners 50 of the child machines A, B, and C can be storedsequentially in page order into a continuous memory area of the MEM-C205 or the HDD 207. At the time of printing out the registered imagedata again, the document image data need not be sorted. As the documentimage data is stored continuously, the image data can be efficientlytransferred to the plotter 80.

[0178] In the above embodiments, the image data read by the scanner 50of the digital copying machine 601 as the parent machine is stored as itis or is stored by compression into the MEM-C 205 or the HDD 207 of theown machine. However, the image data read by the scanner 50 of theparent machine can also be stored into the MEM-C 205 or the HDD 207 ofthe own machine after the image data is edited instead of beingcompressed.

[0179] Further, a recording medium such as a computer-readable opticaldisk like a CD-ROM that is recorded with a program to make the CPU 201(i.e., computer) execute functions of the present invention to controlthe digital copying machines 601 to 604 can also be provided.

[0180] Therefore, when a reading unit such as an optical disk unit thatreads the program from the recording medium is provided in or attachedexternally to the digital copying machines 601 to 604, the recordingmedium such as an optical disk can be mounted on this reading unit. Thereading unit reads the program stored in the recording medium, andinstalls the program into the HDD 207 inside the machines. With thisarrangement, the functions of the present invention can be achieved.

[0181] The application of the present invention to the digital copyingmachine and the image forming apparatus having a plurality of thesecopying machines connected together via a communication line isexplained in the above embodiments. However, the application of thepresent invention is not limited to the above. The present invention canalso be applied to other image forming apparatus such as a digitalmultifunction machine having a copying function, and a facsimile. Theinvention can also be applied to an image forming system having aplurality of image forming apparatuses connected together via acommunication line.

[0182] As explained above, according to the present invention, the user'operation efficiency can be improved, and the copying time can beshortened when making a copy of a large amount of document.

[0183] The present document incorporates by reference the entirecontents of Japanese priority document, 2002-239460 filed in Japan onAug. 20, 2002.

[0184] Although the invention has been described with respect to aspecific embodiment for a complete and clear disclosure, the appendedclaims are not to be thus limited but are to be construed as embodyingall modifications and alternative constructions that may occur to oneskilled in the art which fairly fall within the basic teaching hereinset forth.

What is claimed is:
 1. An image forming system comprising a first imageforming apparatus and a second image forming apparatus that areconnected to each other via a communication line, wherein the firstimage forming apparatus includes an image reading unit that reads imagedata from a document, and the second image forming apparatus includes animage storing unit that stores image data; and a reading controller thatcontrols the image reading unit to read the image data, and controls theimage storing unit to store the image data.
 2. The image forming systemaccording to claim 1, wherein the first image forming apparatus furtherincludes an automatic document feeder that feeds a plurality ofdocuments to the image reading unit one by one, and the readingcontroller controls an operation of the automatic document feeder. 3.The image forming system according to claim 1, wherein the second imageforming apparatus further includes a first image forming controller thatreads the image data from the image storing unit, transmits the imagedata to the first image forming apparatus, and controls the first imageforming apparatus to form an image based on the image data; and a secondimage forming controller that reads the image data from the imagestoring unit, transmits the image data to the second image formingapparatus, and controls the second image forming apparatus to form animage based on the image data.
 4. The image forming system according toclaim 3, wherein the first image forming apparatus further includes afirst data expansion unit that expands compressed image data, the secondimage forming apparatus further includes a data compression unit thatcompresses image data; and a second data expansion unit that expandcompressed image data, the reading controller controls the datacompression unit to compress the image data acquired from the firstimage forming apparatus before storing the image data in the imagestoring unit, and the first image forming controller and the secondimage forming controller include a first expansion controller and secondexpansion controller that controls the first data expansion unit and thesecond data expansion unit to expand the compressed image data,respectively.
 5. The image forming system according to claim 4, whereinthe first expansion controller controls the first data expansion unit toexpand the compressed image data transferred from the second imageforming apparatus to the first image forming apparatus.
 6. The imageforming apparatus according to claim 1, wherein the communication lineis based on a communication interface conforming the Institute ofElectrical and Electronic Engineers 1394 standard.
 7. The image formingapparatus according to claim 1, wherein the image storing unit is a harddisk drive.
 8. An image forming system comprising a first image formingapparatus and a second image forming apparatus that are connected toeach other via a communication line, wherein the first image formingapparatus includes a first image reading unit that reads image data froma document, and the second image forming apparatus includes a secondimage reading unit that reads image data from a document; a imagestoring unit that stores the image data; and a parallel readingcontroller that performs in parallel a control of making the secondimage reading unit read image data from a document that is set on thesecond image reading unit and making the image storing unit store theimage data, and a control of making the first image reading unit readimage data from a document that is set on the first image reading unit,transferring the image data to the second image forming apparatus, andmaking the image storing unit store the image data.
 9. The image formingsystem according to claim 8, wherein the first image forming apparatusfurther includes a first automatic document feeder that automaticallyfeeds a plurality of documents to the first image reading unit one byone, the second image forming apparatus further includes a secondautomatic document feeder that automatically feeds a plurality ofdocuments to the second image reading unit one by one, and the parallelreading controller controls operations of the first automatic documentfeeder and the second automatic document feeder in parallel.
 10. Theimage forming system according to claim 8, wherein the second imageforming apparatus further includes a parallel image forming controllerthat performs in parallel a control of reading image data stored in thesecond image storing unit, and making the second image forming apparatusform an image based on the image data, and a control of reading imagedata stored in the second image storing unit, transferring the imagedata to the first image forming apparatus, and making the first imageforming apparatus form an image based on the image data.
 11. The imageforming system according to claim 10, wherein the first image formingapparatus further includes a data expansion unit that expands compressedimage data; the second image forming apparatus further includes a datacompression unit that compresses image data; the parallel readingcontroller controls the data compression unit to compress the imagedata, and the parallel image forming controller includes an expansioncontroller that controls the data expansion unit to expand the imagedata.
 12. The image forming system according to claim 11, wherein thesecond image forming apparatus further includes a second expansion unitthat expands compressed image data, and the expansion controllercontrols the second expansion unit to expand compressed image data to beformed into an image at the second image forming apparatus, and controlsthe first expansion unit to expand compressed image data transferred tothe first image forming apparatus.
 13. The image forming systemaccording to claim 8, wherein the parallel reading controller includes astoring unit that stores image data in an arbitrary memory area of thesecond image storing unit.
 14. The image forming system according toclaim 8, wherein the parallel reading controller includes a storing unitthat stores image data in a pre-secured memory area of the second imagestoring unit.
 15. The image forming system according to claim 14,wherein the parallel reading controller further includes an areasecuring unit that secures in advance a memory area in the second imagestoring unit in which image data read by the second image reading unitand image data read by the first image reading unit are storedcontinuously; a temporary storing unit that temporarily stores the imagedata read by the first image reading unit in the first image storingunit; a storing unit that stores the image data read by the second imagereading unit in the memory area secured by the area securing unit; and aresidual storing unit that makes the first image forming apparatustransfer image data stored in the first image storing unit when thefirst image reading unit and the second image reading unit completereading all the images from the document, and stores the image datatransferred in a remaining area of the second image storing unit. 16.The image forming system according to claim 8, wherein the second imageforming apparatus further comprises a mode setting unit that sets amemory management mode for managing the second image storing unit, andthe parallel reading controller further includes a first memorycontroller that stores image data into an arbitrary memory area of thesecond image storing unit; a second memory controller that stores imagedata into a pre-secured memory area of the second image storing unit;and an area selection unit that checks a status of the memory managementmode, selects the first memory controller if the memory management isnot set, and selects the second memory controller if the memorymanagement is set.
 17. The image forming apparatus according to claim 8,wherein the communication line is based on a communication interfaceconforming the Institute of Electrical and Electronic Engineers 1394standard.
 18. The image forming apparatus according to claim 8, whereinthe image storing unit is a hard disk drive.
 19. A method of copyingemployed on a system including a plurality of image forming apparatusesconnected to each other via a communication line, the method comprising:setting one of the image forming apparatuses as a master image formingapparatus, and image forming apparatuses other than the master imageforming apparatus as slave image forming apparatuses; making the masterimage forming apparatus acquire image data from the slave image formingapparatus; and making the master image forming apparatus form an imagebased on the image data acquired from the slave image forming apparatus.20. The method according to claim 19, wherein the slave image formingapparatus includes an automatic document feeder, and the method furthercomprising making the master image forming apparatus control anoperation of the automatic document feeder of the slave image formingapparatus.
 21. A method of copying employed on a system including aplurality of image forming apparatuses connected to each other via acommunication line, the method comprising: setting one of the imageforming apparatuses as a master image forming apparatus, and imageforming apparatuses other than the master image forming apparatus asslave image forming apparatuses; making the master image formingapparatus acquire image data; making the master image forming apparatustransfer the image data to a desired one of the slave image formingapparatuses; and making the slave image forming apparatus to which theimage data is transferred form an image based on the image data receivedfrom the master image forming apparatus.
 22. The method according toclaim 21, wherein the slave image forming apparatus includes anautomatic document feeder, and the method further comprising making themaster image forming apparatus control an operation of the automaticdocument feeder of the slave image forming apparatus.
 23. A method ofcopying employed on a system including a plurality of image formingapparatuses connected to each other via a communication line, the methodcomprising: setting one of the image forming apparatuses as a masterimage forming apparatus, and image forming apparatuses other than themaster image forming apparatus as slave image forming apparatuses;making the master image forming apparatus acquire image data from theslave image forming apparatus; making the master image forming apparatusstore image data acquired by the master image forming apparatus and theimage data acquired from the slave image forming apparatus; making themaster image forming apparatus transfer a part of the image data storedto a desired one of the slave image forming apparatuses; and making themaster image forming apparatus form an image based on image dataremaining in the image data and making and the slave image formingapparatus to which the part of the image data is transferred to form animage based on the part of the image data stored, in parallel.
 24. Themethod according to claim 23, wherein the slave image forming apparatusincludes an automatic document feeder, and the method furthercomprising: making the master image forming apparatus control anoperation of the automatic document feeder of the slave image formingapparatus.
 25. A computer program employed on a system including aplurality of image forming apparatuses connected to each other via acommunication line, the computer program making a computer execute:setting one of the image forming apparatuses as a master image formingapparatus, and image forming apparatuses other than the master imageforming apparatus as slave image forming apparatuses; making the masterimage forming apparatus acquire image data from the slave image formingapparatus; and making the master image forming apparatus form an imagebased on the image data acquired from the slave image forming apparatus.26. The computer program according to claim 25, wherein the slave imageforming apparatus includes an automatic document feeder, and thecomputer program further making a computer execute making the masterimage forming apparatus control an operation of the automatic documentfeeder of the slave image forming apparatus.
 27. A computer programemployed on a system including a plurality of image forming apparatusesconnected to each other via a communication line, the computer programmaking a computer execute: setting one of the image forming apparatusesas a master image forming apparatus, and image forming apparatuses otherthan the master image forming apparatus as slave image formingapparatuses; making the master image forming apparatus acquire imagedata; making the master image forming apparatus transfer the image datato a desired one of the slave image forming apparatuses; and making theslave image forming apparatus to which the image data is transferredform an image based on the image data received from the master imageforming apparatus.
 28. The computer program according to claim 27,wherein the slave image forming apparatus includes an automatic documentfeeder, and the computer program further making a computer executemaking the master image forming apparatus control an operation of theautomatic document feeder of the slave image forming apparatus.
 29. Acomputer program employed on a system including a plurality of imageforming apparatuses connected to each other via a communication line,the computer program making the computer execute: setting one of theimage forming apparatuses as a master image forming apparatus, and imageforming apparatuses other than the master image forming apparatus asslave image forming apparatuses; making the master image formingapparatus acquire image data from the slave image forming apparatus;making the master image forming apparatus store image data acquired bythe master image forming apparatus and the image data acquired from theslave image forming apparatus; making the master image forming apparatustransfer a part of the image data stored to a desired one of the slaveimage forming apparatuses; and making the master image forming apparatusform an image based on image data remaining in the image data and makingand the slave image forming apparatus to which the part of the imagedata is transferred to form an image based on the part of the image datastored, in parallel.
 30. The computer program according to claim 29,wherein the slave image forming apparatus includes an automatic documentfeeder, and the computer program further making a computer executemaking the master image forming apparatus control an operation of theautomatic document feeder of the slave image forming apparatus.
 31. Acomputer product containing a computer program employed on a systemincluding a plurality of image forming apparatuses connected to eachother via a communication line, the computer program making a computerexecute: setting one of the image forming apparatuses as a master imageforming apparatus, and image forming apparatuses other than the masterimage forming apparatus as slave image forming apparatuses; making themaster image forming apparatus acquire image data from the slave imageforming apparatus; and making the master image forming apparatus form animage based on the image data acquired from the slave image formingapparatus.
 32. The computer product according to claim 31, wherein theslave image forming apparatus includes an automatic document feeder, andthe computer program further making a computer execute making the masterimage forming apparatus control an operation of the automatic documentfeeder of the slave image forming apparatus.
 33. A computer productcontaining a computer program employed on a system including a pluralityof image forming apparatuses connected to each other via a communicationline, the computer program making a computer execute: setting one of theimage forming apparatuses as a master image forming apparatus, and imageforming apparatuses other than the master image forming apparatus asslave image forming apparatuses; making the master image formingapparatus acquire image data; making the master image forming apparatustransfer the image data to a desired one of the slave image formingapparatuses; and making the slave image forming apparatus to which theimage data is transferred form an image based on the image data receivedfrom the master image forming apparatus.
 34. The computer productaccording to claim 33, wherein the slave image forming apparatusincludes an automatic document feeder, and the computer program furthermaking a computer execute making the master image forming apparatuscontrol an operation of the automatic document feeder of the slave imageforming apparatus.
 35. A computer product containing a computer programemployed on a system including a plurality of image forming apparatusesconnected to each other via a communication line, the computer programmaking the computer execute: setting one of the image formingapparatuses as a master image forming apparatus, and image formingapparatuses other than the master image forming apparatus as slave imageforming apparatuses; making the master image forming apparatus acquireimage data from the slave image forming apparatus; making the masterimage forming apparatus store image data acquired by the master imageforming apparatus and the image data acquired from the slave imageforming apparatus; making the master image forming apparatus transfer apart of the image data stored to a desired one of the slave imageforming apparatuses; and making the master image forming apparatus forman image based on image data remaining in the image data and making andthe slave image forming apparatus to which the part of the image data istransferred to form an image based on the part of the image data stored,in parallel.
 36. The computer product according to claim 35, wherein theslave image forming apparatus includes an automatic document feeder, andthe program further making a computer execute making the master imageforming apparatus control an operation of the automatic document feederof the slave image forming apparatus.
 37. An image forming apparatusconnected to another image forming apparatus via a communication line,the image forming apparatus comprising: a data acquiring unit thatacquires image data from the another image forming apparatus; and animage forming unit that forms an image based on the image data acquiredfor the another image forming apparatus.